A few quick, interesting facts about a different topic each entry. It's like an apple a day: pleasant, good to have, and pocket-sized.

Wednesday, October 19, 2011

Apple #553: Kaleidoscopes

I noticed that a lot of my entries lately have been about things that are white. Cotton balls. White caterpillars. Pantyhose. Well, that's not white, but it's blah-colored. I thought it was time for an entry with some color! Let's brighten things up around here! So I give you kaleidoscopes.

He was studying light and mirrors and optics. He was a pretty smart dude, by the way. He also invented the forerunner of the lighthouse, among other things. His method of calculating the angle at which light must strike a given surface to achieve maximum polarization of light, a calculation known as Brewster's Angle, is still used today in building microscopes and lasers and fiber optics, in adjusting radio signals, in meteorology, and all sorts of other applications.

So while he was doing all that investigating of light and mirrors and polarization, he noticed that the light bouncing off of two mirrors created patterns and colors that were visible on other surfaces. Long story short, he put the two mirrors inside a tube with an opening to look into it at one end and bingo, he had a kaleidoscope.

The word, by the way, is a compound word made of several Greek words. It breaks down like this: kalos (beautiful) + eodos (shape) + scopeo (to look at).

Dr. Peter Roget -- yes, the Roget of thesaurus fame -- said of the kaleidoscope, "In the memory of man, no invention, and no work, whether addressed to the imagination or to the understanding, ever produced such an effect."

Kaleidoscopes were an instant hit. People all over Britain and the United States were buying one or more for their homes. They were quite the Victorian fad.

With visions like this, it's easy to see why the gadgets became so popular.(Grapevine kaleidoscope available from Victorian Connection)

One of the things that will determine what shape you see at the end of the tube is how many mirrors are inside the tube. Regardless of how many they are, the mirrors run the full length of the inside of the tube.

Most kaleidoscopes have two mirrors. They produce the image you see the most often. Some people call these shapes mandalas.

The image looks like a circle but when you look closely, you'll see it's actually a decahedron (10-sided object). The center is a five-pointed star.(Photo from possumjim and elizabeth)

Very few kaleidoscopes use four mirrors, but this one does. Four mirrors produce a series of rectangular images that are on opposite sides of a center line.(Photo and kaleidoscope from Peggy & Steve Kittelson)

The angle of the mirrors also affects the image you'll see. The smaller the angle, the greater the number of reflections. In a two-mirror kaleidoscope, if the mirrors are placed at a 10 degree angle, the number of reflections is 360 degrees in a circle / 10 degrees minus 1, or 35 reflections. If the mirrors are placed at a 40 degree angle, there will be 360 / 40 -1 or 8 reflections.

As you can imagine, making sure those mirrors have straight, aligned edges can make a lot of difference. Kaleidoscope makers do their best to make sure everything is lined up just right, but sometimes the mirrors wind up out of alignment.

In this one, something about the position of the mirrors wasn't aligned quite right.(Photo from possumjim and elizabeth)

Some kaleidoscopes have an eyepiece at the front. That front lens is a diopter lens and it isn't involved in any of the reflecting activity in the body of the kaleidoscope. Its purpose is to magnify the image that you see at the end of the tube, making everything appear sharper and clearer to your eye. The longer the kaleidoscope, the more likely it'll have that front diopter, and the stronger it will have to be.

Many kaleidoscopes also contain liquid. This is to make sure the pieces slide around slowly and easily, rather than chunking and slipping and rattling abruptly into place. Often the liquid is mineral oil (a.k.a. baby oil) or glycerin. More recently, kaleidoscope makers use silicone, which is less prone to leaking.

This kaleidoscope has two mirrors, but it's oil-filled, which is what gives everything that rich, liquid feel.(Photo and kaleidoscope by Peggy & Steve Kittelson)

A lot of kaleidoscopes being made today include found objects. Not just glass pieces, but other little tidbits like springs or buttons or doll eyes. My great uncle made a kaleidoscope. It had mostly pieces of glass in it but there were also a couple squares of window screen in there.

This kaleidoscope uses all sorts of seashells. I'm pretty sure that Judith Paul and Tom Durden made this one. They make a lot of seashell kaleidoscopes.(Photo from balluun)

Some kaleidoscopes enclose the bits of glass and other goodies not in a chamber at the end of the tube but outside of it on a wheel which the user turns. Sometimes the shapes are fixed in place in the wheel, and sometimes the shapes are free-moving inside the glass wheel.

This is a three-mirror double-wheel kaleidoscope. This photo shows how the wheel is connected to the body. You can see that there are two layers of glass in the wheel, which will make for additional reflections and colors.(Photo and kaleidoscope by Koji Yamami)

This is what you see when you look through one of his 3-mirror wheel kaleidoscopes. This one, I think, must be only a single-wheel.(Photo and kaleidoscope by Koji Yamami)

Another variation is to use a tube instead of a wheel at the end of the kaleidoscope. The tube can be rotated or slid back and forth to change the scenery.

This is an oil-filled stained glass tube kaleidoscope.(Photo and kaleidoscope by Koji Yamami)

The glass inside the tube are drawn and twisted to make very delicate shapes.(Photo and kaleidoscope by Koji Yamami)

Once you realize that the basic components themselves can have so many variations, all sorts of possibilities start to open up. All you need is a tube -- which doesn't even have to be circular -- some mirrors to put inside it, and some shapes that will let at least some light through. From there, the sky is the limit.

This is what you see when you look in the wine cask kaleidoscope.(Photo and kaleidoscope by Mitsuru and Yuriko Yoda)

Kaleidoscopes that include images of the thing you point them at are called teleidoscopes. Instead of the end of the scope being a piece of glass with black backing on it, it's another lens. So the mirrors inside the tube are reflecting the image of what's outside the tube.

This is the view through a teleidoscope looking up at the treetops.(Photo by jcarwash31 on Flickr, sourced from Rikki's Teleidoscope)

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